Picture receiver



INVENTOR AUGUST KARGLUS ATTORNEY June l2, 1934. A. KARoLus PICTURE RECEIVER Filed Feb. 24, 195o fIJJYYJf/n/J//f//X-X ,17

Patented June 12, 1934 PICTURE RECEIVER.

August Karolus, Leipzig, Radio Corporation of A Delaware Application February 24 In Germany 3 Claims.

The invention is concerned with the transmission of static or still pictures, or of moving pictures, and more particularly with the case where scanning or exploration and re-creation are effected not by movements of luminous points or diaphragme, but rather by the switching of cellscreens. Hence, the picture surface consists of rows of points comprising photo-electric cells (selenium, or photo-cells) for the transmitter apparatus and luminescent cells, such as glow-discharge lamps, for the receiver apparatus, while switches rotating in synohronism and under cophasic conditions are provided so as to take care that homologous cells of the row are interconnected. Between the two change-over switches are to be inserted the amplifier and transmission means.

It is known in the prior art that change-over switches of this kind, both for entire groups of rows as well as for separate or distinct cells inside a given row of points, may consist of current-distributers driven by a motor. One or more slip brushes in rapid alternation make contact with contacts which are associated with the respective groups or with separate elements. Furthermore, inertialess switching devices are known whereby cell screens disposed in the interior of vacuum tubes in a way known from the Braun tube are to be switched over by moving pencils of electrons, these pencils of electrons being set into rotation, for example, bythe action of a rotary magnetic field.

The mechanical change-over switches of the kind rst named are unsuited for ne picture screens which comprise a great number of cells, on the ground that the dimensions and circumferential speeds would have to be inadmissibly high where so many contacts are needed. In the case of devices of the second kind, the main disadvantages reside in the fact that the cell screens including all of their contacts, insulated surfaces, etc. have to be accommodated inthe interior of thermionic tubes, and this would be attended with considerable difliculties as regards assembling of the tubes and their treatment from a vacuum or evacuating viewpoint.

The present invention obviates the above named difficulties by providing a combination of a mechanical and an electronic change-over switch, in such manner that the former effectsV the circuit-changes "or change-over between groups of cells (which changes proceed at a relatively low rate of speed), while the latter insures the distribution of current over the constituent elements of each cell group or bank, an opera- Germany, assigner to merlca,` a corporation of 1930, Serial N0. 430,766`

tion which must proceed far faster. In this manner itis feasible to make picture surfaces of any desired size and neness of grain, because the inertialess device and the screen need not form a unit from a constructional viewpoint. The arrangement of the vacuum tube may be simplied, although the contact frequency may be extremely high.

Fig. 1 of the drawing illustrates one embodiment which is shown by way of example, and Fig. 2 discloses a modification of Fig. 1.

The cells comprising photoelectric cells for the transmitter and glow-discharge vessels for the receiver apparatus, are arranged in vertical groups, being respectively denoted by Roman numerals I, II, III, etc., while the place or position of each individual element inside a given group is designated by Arabic numerals 1, 2, 3, etc. Only a small number of the total cells has been designated. The receiving circuit is here fed with D. C., although it could be supplied also with A. C. 20 denotes the mechanical, and

21 the electronic change-over device. The former has disposed upon its periphery T many stationary contacts 9, 9, 9, etc. at equal inter- 80 vening distances, while opposite thereto rotates V a star 01 spider of (r-D many distributer contacts 10, 10', 1G", etc., all of the latter forming equal angles between themselves. With -this arrangement which is well known in the prior art, it is possible that even l/r revolution of the distributer star suices in order that consecutively all of the r groups of cells I, Il, III, etc. may be switched-in in uniform sequence. The electronic change-over switch 21 is furnished with 90 anodes 11, 11', 11", etc., of a number equal to r, uniformly distributed over the circumference, said anodes being coordinated to the respective places of elements l, 2, 3, etc., as can be readily seen from the drawing. The pencil of electrons, 12, issuing from a common cathode 13 and striking the electrodes 11, l1', 1l", and whose intensity is governed by the intensity of the picture signal (for which purpose there are used controlling means well known in the prior art), is set into rotation by defiector coils 14, l5, and 16,

17 respectively, energized under dephased conditions. Its circumferential speed naturally must bear a constant relation to that of the distributer star in switch 20; to be more precise, when 105 nl is the speed of rotation of the switch 20, and

112 is that of switch 21, then the said relation is given byV the expression n2/1L1=r2. In other words, the electron pencil rotates many times faster than the distributer star of switch 20.

sistance inserted in The poles of the receiving circuit are denoted by 18 and 19. At the instant shown in the drawing, the current iiows from 18 by way of distributer arm 10, contact 9, cell 5 into group IV, anode 11 and cathode 13 toward 19. In spite of the high speed of switching, all of the contacts areaccurately -established by virtue of the absence of inertia and the accuracy of control of the electron pencil. Indeed, the switching-in and switching-out are accurately defined, and there arise no diiiculties of insulation.

The mechanical change-over switch 20 need not be designed in a way as here shown. Indeed, its place may be taken by an ordinary distributer comprising a single circulating or rotating contact member, though in this instance the speed of rotation must be r times higher.

As regards the construction of the electronic change-over device or switch 2i reference must be made here to the disclosure, instructions and examples given in the prior art. One particular advantage of the arrangement as here shown resides in that, in the presence of r2 picture points, the cathode-ray tube (electronic tube) 21 needs to have only r lead-ins brought to the electrodes 11, 11', 11", etc., contradistinct from what is true of earlier suggestions where all of the cells are switched in and out by purely electronic means and where T2 lead-ins are furnished in order to establish connection with the cell screens located outside the tube. This simplification, as will be noted, is insured in the present invention by combining the mechanical group or bank switch with an electronic change--over device for the individual cells.

Since it would hardly be possible to convey a maximum current for energizing the luminous cells by way of the electron pencil of the switch .tube 21, a mediately acting electronic distributer arrangement may be used in which the cathode ray-pencil subject to intensity control by the receiver, does not carry the operating current of the cell screen, but serves merely as a path of least resistance for releasing the working current. For this purpose could be employed, for example, the instantaneously varying charges set up by the rotating electron pencil at distinct control electrodes. For instance, the rotating cathode ray-pencil controlled in its intensity by the incoming current may be used to more or less charge up negatively grid electrodes of amplier systems. The anode current which will be caused to thus decrease more or less diminishes the potential diiference across the ends of a reits circuit. This potential difference acts in the form of a counter E. M. F. in the circuit of the luminous cell and its source. Since the counter E. M. F. diminishes as the control electrodes are charged up negatively, a correspondingly reinforced current impulse associated with greater brightness is made to flow across the luminous cell. The grid electrode, of course, together with the cathode coordinated to it must be united by a high resistance in order that unduly fast leaking away of the negative charge must be precluded.

A somewhat diiferent circuit arrangement is shown in Fig. 2 in which of the groups of luminous cells only banks I, II and III are illustrated, while inside these only cells 1 and 2 are indicated. The group supply leads are united with the contacts 9, 9', 9, etc. of the mechanical change-over switch 10 by which the current is able to flow from the positive pole of the source 18 through the particular luminous cell which happens to be in circuit. The rotating electron pencil l2 impinges upon the distributer electrodes 1l, 11', 11 con-- fined inside the vacuum vessel, from which leads are brought to the control grids 36, 37, which are associated with the coordinated cathodes 38, 39, by way of high resistance 40, 41.

These amplifier systems should most suitably be provided with a high reciprocal amplification factor so that, in the state of rest or when unenergized, a comparatively strong current will iiow by way of the anodes 32, 33 through the resistances 34, 35. The plate current source for supplying plate current through anodes 32, 33, shown, is denoted by 31, while 30 designates the joint heating battery for all of the amplifier cathodes 38, 39, etc. At suitable points on the anode resistances S4, 35, a biasing potential is taken off for the control grids 24, 25, which govern the fiow of thev current of the luminous cells. For this purpose the anodes 22, 23, and the hot cathodes 26, 27 are provided. The electrodes 24, 25, etc. are united by way of high grid resistances 28, 29, with the cathodes 26, 27. Reciprocal ampliication and biasing potential are so chosen that the fiow of current in these systems (22-26, and 23-'27 respectively) is shut off in unenergized condition. Now, as soon as a more or lessstrong electronic current 12, as shown, happens to impinge upon the distributer electrode 11 whenever the picture element in the transmitter is more or less bright, then the grid electrode 36 becomes charged negatively to a marked degree, the anode current in the resistance 34 decreases, and the potential at the point where the potential for grid electrode 24 is derived becomes more markedly positive, with the result that the circuit 22--26 becomes more or less permeable. As a consequence, a brightening current of regulated intensity will be caused to flow from the positive pole 18 by way of the distributer arm 10, contact 9 glowdischarge cell l in group III, plate 22 and lament 26 to the return conductor 19 united with the negative battery poie. The diiferent inter-electrode gaps will thus be opened up as the cathoderay pencil 12 travels over the distributer electrodes in a way free from sluggishness, so that the flashing up of the various cells along a bank can be accomplished at a high rate of speed.

The accompanying drawing and specication show by way of example one of the several forms which the invention may assume, but I believe myself to be entitled to make and use any and all modifications such as would readily suggest themselves to those skilled in the art, and such as would fall fairly within the spirit and scope of the invention as set forth in the appended claims.

Having now described myv invention, what I claim and desire to secure by Letters Patent is the following:

1. In a television system, a plurality of image producing points, a plurality of independently energizable sets of conductors arranged in intersecting patterns and having one of said image producing points connected at each intersection,

a thermionic device connected with each conductor of one of said sets, means for normally preventing current flow through said thermionic devices in the absence of impressed signals thereon,

an inertialess controlling element for energizing sequentially thermionic device to produce trigger action in accordance with received signals so as to supply controlled currents to each of the conductors of one of said sets in sequence, and mechanical means for limiting the effect of said l 1,962,447 supplied energy to a single point of each of said conductors.

2. In a television system, a plurality of image producing points, a plurality of independently energizable sets of conductors arranged in intersecting patterns having one of said image points connected at each intersection, a thermionic relay device connected with each conductor of one of said sets, a second thermionic relay device connected with each of said first-named thermionic devices, means for normally maintaining each of said second-named thermionic devices in an operative state, means normally responsive to a current oW through each of said operative thermionic devices for biasing each of said rstnamed thermionic devices to cut-off, a cathode ray instrumentality for inuencing each of said second-named thermionic relay devices sequentially for biasing said amplifiers in sequence to substantially a cut-off point for increasing the flow of current through each of said first-named thermionic relay devices so as to sequentially pass current through each conductor of one of said sets, and a mechanical means for selecting the point at which the current passing through each conductor of said last-named set is effective.

3. In an electro-optical image producing system, a plurality of light producing elements arranged at the intersection of a plurality cf conductors arranged in the form of abscissi and ordinates Whose concurrently energized intersections determine the instantaneous light values produced from said elements, means for sequentially energizing the abscissa conductors at predetermined rate, a iirst thermionic relay connected with each ordinate conductor, a second series of normally operative thermionic relays having the output circuit connected With the input circuit of each rst thermionic relay to bias each rst thermionic relay normally to cut-off during periods of operation of each second relay, and an electronic means for sequentially triggering the relay of the second series so as to reduce the space current through the relays of the second series and thereby render the relays of the first series operative in sequence to pass current through the ordinate conductors.

AUGUST KAROLUS. 

